Ubuntu on Dell Inspiron 9400

Problems, in short:

• Screen tearing
• USB audio unusable
• No way to adjust brightness

Upgrading from a previous version of Ubuntu proved that you have to reinstall every application that don't come as standard. This includes the graphics drivers (proprietary). Without it, you'll get the default GNOME desktop, with no visible change from 10.10.

Unity and screen tear
Installing the 'recommended drivers' option, you're back to an ugly bootscreen, and the new GNOME replacement – Unity – is in effect. This is where I get random tears on the screen. Whether you browse, just idle or type in a document. It doesn't matter. I haven't tried the other drivers (version 173 etc.), but I have no reason to think they should be better. I wasn't able to screen-capture them. These tears is something I've never had with any previous Ubuntu version, but it also didn't happen with the proprietary drivers not installed on 11.04.

Unresolved issues
Since 10.10 Maverick Meerkat

• Sound is a nightmare if you're unlucky enough to have to use USB audio, like me. When adjusting using the "media buttons" on front of the PC, you get a horrible screeching sound, no matter how high the volume is. You have to manually adjust the volume on the panel, or on your speakers, to not get this. The difference between adjusting on the panel and using the media buttons, seems to be that the subwoofer level (as indicated in 'sound preferences' - click the sound-icon) seems to be at max whilst altering the volume in the panel, and keeping it there seems to have no such shrieking sound.
• Adjusting brightness is a pain-in-the-arse. Just try it. It jumps 2-3 steps instead of one (Inspiron don't have that many levels to begin with) with the result that you never get the appropiate brightness. It doesn't help that there's no easy way to add a simple brightness applet anywhere in Unity.

Opera
Opera is generally slow and unresponsive in Ubuntu 11.04. It might not be much worse than in previous versions, but it feels as so. Largely a subjective claim, though.

Compiz effects
Don't try to enable them. The most useful feature, desktop zoom, is so laggy it's unusable. Everything just seems to be much slower and more unresponsive than in 10.04/10.10.

Keep to 10.04
I recommend everyone to keep using 10.04 Lucid Lynx. It has the issue with screen flickering and an audio issue (going to max at one click), but at least there are fixes for this, see the 10.04 entry.
I haven't been able to find out how to fix the USB audio or brightness problem. These have been unresolved since 10.10.